The current state of the art treatment for minimally invasive surgical applications requiring tissue cutting or removal relies on high-power laser pulses for precise tissue ablation. Currently the holmium-doped yttrium aluminum garnet (Ho:YAG) and potassium-titanyl-phosphate (KTP) (having a typical penetration depth of 350 μm) and carbon dioxide (CO2) (having a typical penetration depth of 5 μm) lasers are used for a variety of procedures in urology, orthopedics, ENT, gastroenterology, and general surgery to address the wide range of surgical needs for high-power laser-ablation applications to enable faster, more efficient treatments and reduce operating and anesthesia time. Alternatively, the neodymium-doped yttrium aluminum garnet (Nd:YAG) laser has a deeper penetration (˜2-3 mm) in soft tissues and is useful for coagulation. Applications specific to the Ho:YAG in urologic surgery involve the urethra (ablation, incision, tumor removal), bladder (bladder neck incisions, calculi, tumors, soft tissue ablation), ureter (calculi, incision, tumor removal), prostate (HoLAB, HoLEP, TVIP), kidney (calculi), and in some cases coagulation of blood. Clearly, the Ho:YAG laser has been adopted by the medical field due to the acceptable performance of the existing device and its ability to transmit through optical fibers.
An article authored by Nathanial M. Fried et al. titled “High-power thulium fiber laser ablation of urological tissues at 1.94 μm” (Journal of Endourology Vol. 19(1), pages 25-31, 2005) describes a 40 W thulium fiber laser operating at a wavelength of 1.94 μm delivered radiation in a continuous-wave or pulsed mode (10 milliseconds (msec)) through either 300-μm- or 600-μm-core low —OH silica fibers for vaporization of canine prostate and incision of animal ureter and bladder-neck tissues. The thulium fiber laser vaporized prostate tissue at a rate of 0.21±0.02 g/min. The thermal-coagulation zone measured 500 to 2000 μm (0.5 to 2 mm), demonstrating the potential for hemostasis. Laser incisions were also made in bladder tissue and ureter, with coagulation zones of 400 to 600 μm. They concluded that the thulium fiber laser has several potential advantages over the holmium laser, including smaller size, more efficient operation, more precise incision of tissues, and operation in either the pulsed or the continuous-wave mode. However, before clinical use will be possible, development of higher-power thulium fiber lasers and shorter pulse lengths will be necessary for rapid vaporization of the prostate and more precise incision of urethral/bladder-neck strictures, respectively. See also Fried, N. M., High-power laser vaporization of the canine prostate using a 110 W thulium fiber laser at 1.91 μm, Lasers in Surgery and Medicine, 36:52-56 (2005).
There are, however, several limitations associated with these current devices:                1. Insufficient control of the damage zone: These lasers can cause significant thermal damage during soft-tissue incision, with a minimal thermal damage zone of 400-500 μm or greater. This collateral thermal damage outside the irradiated tissue zone is undesirable for many procedures requiring precise ablation, such as ureteral strictures (abnormal narrowing of the lumen of a ureter, which causes functional obstruction) and urethral strictures (abnormal narrowing of the urethra) and bladder-neck contractures.                    2. Non-ideal pulse structure: The pulse structure of the clinical Ho:YAG system is limited to pulse durations of 200 to 1000 μsec pulses (pulses that are too long to achieve stress-confined ablation), leaving this laser in a thermally confined regime which is not optimal for tissue cutting or perhaps coagulation.                        3. Inefficient power requirements: The clinical Ho:YAG laser is inefficient at high-power operations and requires a 220-V source and large system hardware.        4. Inefficient fiber coupling efficiency: The clinical Ho:YAG laser-beam diameters are large and hard to focus into small optical fibers (those which are approximately 200-μm diameter), which complicates use in flexible ureteroscopes in the upper urinary tract.        
U.S. Pat. No. 5,459,745 titled “TM:YALO, 1.94-MICRON, SOLID STATE LASER” was issued to Esterowitz et al., and is herby incorporated by reference. This patent describes a thulium-doped solid state laser capable of operation at a wavelength that has a shallow absorption depth in tissue. The laser included a laser cavity defined by first and second reflecting surfaces opposing each other on an optical axis, a thulium-doped YALO crystal disposed in the cavity, and a pump source for pumping the crystal with a pump beam at a preselected wavelength to enable the crystal to emit a most preferred 1.94 micron laser output. The thulium-doped YALO crystal is preferably an A-cut crystal. Such alignment of this material provides a reliable mode at 1.94 microns which has excellent tissue absorption characteristics for medical applications. The length l of the crystal, the concentration N of the dopant and the transmissivity T of the output coupler, which define an expression NUT, can be varied as long as the expression NUT produces a value which does not exceed about 0.32 centimeters.
An article authored by A. F. El-Sherif and T. A. King titled, “Soft and hard tissue ablation with short-pulse high peak power and continuous thulium-silica fibre lasers” (Lasers in Medical Science, Vol 18, pages 139-147, 2003) is incorporated herein by reference. The article describes investigating the use of thulium lasers operating near ˜2 μm for various medical applications. The newly developed Tm3+ silica fibre laser in Q-switched and CW operation was investigated to determine its efficiency in the interaction with soft and hard tissues. The interaction was investigated using a free-running continuous (CW) Tm3+-doped fibre laser (wavelength 1.99 μm, with self-pulsation ranging over 1 to few tens of microseconds) and for novel Q-switched operation of the same fibre laser (pulse durations from 150 to 900 ns and pulse repetition rates from 100 Hz to 17 kHz). Residual damage and affected zones using the Q-switched laser were nearly six times smaller than using the CW fibre laser for about 50 s of exposure time, and increased with pulse repetition rate. The energy required to ablate tissue with the Q-switched fibre laser ranged from 0.2 to 0.6 kJ/cm3 and was significantly smaller than that for the CW fibre laser of 153 to 334 kJ/cm3. Under both high-resolution reflected optical microscopy and histological examination, tissue crater depths were observed as cleanly cut with smooth walls and minimal charring in the case of Q-switched operation of the fibre laser. This study is the first direct comparison of tissue interaction of short-pulse (Q-switched) and CW Tm3+-doped silica fibre lasers on crater depth, heat of ablation and collateral damage. The Q-switched Tm3+-doped silica fibre laser effectively ablates tissue with little secondary damage.
U.S. patent application Ser. No. 11/856,646, tiled “ELECTROSURGICAL APPARATUS AND METHODS FOR TREATMENT AND REMOVAL OF TISSUE” by Dahla, et al. is incorporated herein by reference. This patent application describes an apparatus and methods for ablating, severing, cutting, shrinking, coagulating, or otherwise modifying a target tissue to be treated. In a method for treating a target tissue, an active electrode of an electrosurgical probe is positioned in at least close proximity to the target tissue in the presence of an electrically conductive fluid. A high frequency voltage is then applied between the active electrode and a return electrode, wherein, the high frequency voltage is sufficient to volumetrically remove (ablate), sever, or modify at least a portion of the target tissue. The probe comprises a multi-lumen shaft having a plurality of internal lumens, and a return electrode coil oriented substantially parallel to the shaft distal end. The active electrode may be in the form of a metal disc, a hook, or an active electrode coil. In the latter embodiment, the active electrode coil is typically arranged substantially orthogonal to the return electrode coil. Methods of making an active electrode coil, a return electrode coil, and an electrosurgical probe are also disclosed.
U.S. patent application Ser. No. 11/747,663 titled “APPARATUS AND METHOD FOR ABLATION-RELATED DERMATOLOGICAL TREATMENT OF SELECTED TARGETS” by DeBenedictis; Leonard C., et al. is incorporated herein by reference. This patent application describes a treatment for skin containing selected targets that provides feedback in response to a measurement enabled by the ablation of holes. The inventive apparatus includes an electromagnetic source configured to emit ablative electromagnetic energy, a delivery system, a sensing element, and a controller. The delivery system can be configured to receive ablative energy from the electromagnetic source and deliver it to multiple discrete locations at the selected region to form a pattern of discrete holes in epidermal and dermal tissue of the skin. The lipid content a portion of the tissue can be evaluated using a sensing element. At least one pulse of electromagnetic energy is delivered to the skin under control of a controller in response to the result of a measurement by the sensing element. The apparatus may include a positional sensor to provide additional dosage control, particularly when the inventive method is used with a continuously movable handpiece.
U.S. Pat. No. 5,769,840 titled “MICROSURGERY USING ALTERNATING DISRUPTIVE AND THERMAL LASER BEAM PULSES” by Schirmer; Kurt E is incorporated herein by reference. This patent describes a method and an apparatus for conducting microsurgery on human or animal tissue which includes alternately providing an Argon laser beam pulse and a YAG laser beam pulse in a cycle which is equal to or less than one second. A robotic device including piston and cylinder arrangements is provided for activating the control keys on a control panel associated with the Argon and YAG lasers.
U.S. Pat. No. 5,656,186 titled, “METHOD FOR CONTROLLING CONFIGURATION OF LASER INDUCED BREAKDOWN AND ABLATION” by Mourou; Gerard A. et al. is incorporated herein by reference. This patent describes a method for laser induced breakdown of a material with a pulsed laser beam where the material is characterized by a relationship of fluence breakdown threshold (Fth) versus laser beam pulse width (T) that exhibits an abrupt, rapid, and distinct change or at least a clearly detectable and distinct change in slope at a predetermined laser pulse width value. The method comprises generating a beam of laser pulses in which each pulse has a pulse width equal to or less than the predetermined laser pulse width value. The beam is focused to a point at or beneath the surface of a material where laser induced breakdown is desired. The beam may be used in combination with a mask in the beam path. The beam or mask may be moved in the x, y, and z directions to produce desired features. The technique can produce features smaller than the spot size and Rayleigh range due to enhanced damage threshold accuracy in the short pulse regime.
U.S. Pat. No. 5,112,328 titled “METHOD AND APPARATUS FOR LASER SURGERY”, by Taboada; John et al. is incorporated herein by reference. This patent describes an apparatus and method for laser surgery in which laser energy, pulsed or continuous, is focused to a focus spot of ten to thirty microns which is located within tissue, or the like to cause highly localized heating. The pulsed radiation is in the TEM(oo) mode, has a wavelength of approximately 1064 nanometer, the pulses being not in excess of 100 nanoseconds and the pulse rate being approximately 2000 per second. Where the laser beam is continuous or pulsed, it has a wavelength of approximately 1400 to 1800 nanometer, or in photoablative modes, having a wavelength of 190 to about 300 nanometers. The focus spot may be caused to move relative to the axis of a handpiece; and liquid may flow across the exposure site to remove debris. A handpiece may have an endoscope including a glass contact tip at its distal end to receive light and to acquire an image of the exposure site probes for eye surgery include a quartz rod in a sheath, the quartz rod having a beveled distal end surface through which the laser radiation is emitted and may have infusion and aspiration passages with ends coplanar with the beveled end surface of the quartz rod.
U.S. Pat. No. 6,096,031 titled, “HIGH REPETITION RATE ERBIUM: YAG LASER FOR TISSUE ABLATION” and U.S. Pat. No. 6,395,000 titled, “HIGH REPETITION RATE ERBIUM: YAG LASER FOR TISSUE ABLATION” both by Mitchell; Gerald M. et al. are incorporated herein by reference. These patents describe a medical laser system for ablating biological material. The system includes an Erbium:YAG gain medium capable of generating a pulsed output having a wavelength of 2.9 microns. The laser is optimized to generate a pulsed output having a repetition rate of at least 50 hertz and preferably at least 100 hertz. The output is delivered to the target tissue via an optical fiber. Preferably, a suction source is provided to aspirate the tissue as it is being ablated. The erbium laser system provides accurate ablation with minimal damage to surrounding tissue.
U.S. Pat. No. 6,529,543 titled “APPARATUS FOR CONTROLLING LASER PENETRATION DEPTH”, by Anderson; R. Rox et al. is incorporated herein by reference. This patent describes systems and tools for controlling the optical penetration depth of laser energy, e.g., when delivering laser energy to target tissue in a patient. The systems and tools control the optical penetration depth (OPD) by controlling the incident angle at which the laser energy is delivered to the target area of the patient. Embodiments of the invention include an optical coupler that permit a user to vary the incident angle and thereby selectably control the OPD of incident laser energy. Fabricating the optical coupler to have a refractive index greater than that of the target tissue can enhance the range of selectable OPDs. The laser energy, which is delivered to the desired depth, can cause alteration of the target tissue by, e.g., heating, ablation, and/or photochemical reaction.
U.S. Pat. No. 6,310,900 tiled “LASER DIODE PACKAGE WITH HEAT SINK” by Stephens; Edward F. et al. is incorporated herein by reference. This patent describes a laser diode assembly including a laser diode having an emitting surface and a reflective surface opposing the emitting surface. Between the emitting and reflective surfaces, the laser diode has first and second surfaces to which a first heat sink and second heat sink are attached, respectively, via a solder bond. A spacer element is disposed between the first and second heat sinks and is below the laser diode. The spacer element has a width that is chosen to provide optimum spacing between the first and second heat sinks. The spacer element has a height that is chosen to place the emitting surface of the laser diodes at a position that is substantially flush with the upper surfaces of the heat sinks. A substrate is positioned below the first and second heat sinks and is attached to these two components usually via a solder bond. The substrate is preferably of a nonconductive material so that electrical current flows only through the heat sinks and the laser diode. To properly locate the spacer element, the substrate may include a locating channel into which the spacer element fits. Each of the heat sinks is coated with a solder layer prior to assembly. Once the components are placed in their basic assembly position, only one heating step is needed to cause the solder layer on the heat sinks to reflow and attach each heat sink to the adjacent laser diodes and also to the substrate.
U.S. Pat. No. 6,228,076 titled “SYSTEM AND METHOD FOR CONTROLLING TISSUE ABLATION” by Winston; Thomas R. et al. is incorporated herein by reference. This patent describes a control system and method for controlling tissue ablation uses optical time domain reflectometry data to differentiate abnormal tissue from normal tissue, and to control ablation of abnormal tissue by controlling a tissue ablative apparatus. Using data provided by an interferometric apparatus, the control system provides control signals to the tissue ablative apparatus, controlling activation of the tissue ablation apparatus so that normal tissue is left untreated while abnormal tissue is ablated.
U.S. Pat. No. 4,733,660 titled “LASER SYSTEM FOR PROVIDING TARGET SPECIFIC ENERGY DEPOSITION AND DAMAGE” by Itzkan; Irving is incorporated herein by reference. This patent decribes a hand piece for use with a laser includes a scanning mechanism which controls dosimetry of radiation applied to a target area which is adjustable to limit thermal diffusion from the light absorbing portion of the irradiated target site for selective target specific energy deposition. When used for dermatologic purposes, the adjustable scanning mechanism permits radiation to impinge on tissue for a predetermined period of time for the selective necrosis of highly-filled blood vessels, while leaving adjacent tissue and empty blood vessels undamaged. The dwell time of the laser beam is designed to match the diffusion time for thermal destruction of the wall of the abnormal vessel, with the dwell time adjusted by the scanning rate.
U.S. Patent Application Serial No 2002/0045811 titled “LASER ABLATION PROCESS AND APPARATUS” by Kittrell, Carter is incorporated herein by reference. This patent application describes a laser catheter wherein optical fibers carrying laser light are mounted in a catheter for insertion into an artery to provide controlled delivery of a laser beam for percutaneous intravascular laser treatment of atherosclerotic disease. A transparent protective shield is provided at the distal end of the catheter for mechanically displacing intravascular blood and protecting the fibers from the intravascular contents, as well as protecting the patient in the event of failure of the fiber optics. Multiple optical fibers allow the selection of tissue that is to be removed. A computer controlled system automatically aligns fibers with the laser and controls exposure time. Spectroscopic diagnostics determine what tissue is to be removed.
U.S. Pat. No. 5,897,549 titled “TRANSFORMATION OF UNWANTED TISSUE BY DEEP LASER HEATING OF WATER” and U.S. Pat. No. 6,083,217 titled “DESTRUCTION FOR UNWANTED TISSUE BY DEEP LASER HEATING OF WATER” by Tankovich are both incorporated herein by reference. These patents describe a process for treating relatively deep formations of undesirable sub-epidermal tissue by heating water in the formations with a laser to denature proteins therein. A laser beam is operated to irradiate a target region of highly vascularized dermal tissue or mechanically traumatized tissue in a blood-circulating living being, such as a human. The laser light preferably has a wavelength of about 1.45-1.68 microns (micrometers). This operating parameter provides the laser beam with a low enough water-absorption coefficient to facilitate adequate penetration into the target area while still providing enough energy to heat water to a temperature capable of spatially conforming vascularized tissue in the target area. Treatment pursuant to the above-cited patents may be applied to medical procedures applied to the skin to treat sub-epidermal tissues for a variety of aesthetic treatments. These include treatments for highly vascular regions of sub-epidermal tissue (such as strawberry hemangioma, spider veins, telangiectasia, Karposi's sarcoma, and the like), as well as regions of dermis collagen mechanically damaged due to various reasons (such as frequent muscular contraction, burning, traumatic irritation, worsening of mechanical damage due to environmental exposure, and the like), and aesthetic improvement of scars.
An article authored by Thomsen, Sharon titled “Pathological Analysis of Photothermal and Photomechanical Effects of Laser-Tissue Interactions” (Photochemistry and Photobiology, Vol. 53, No. 6, pages 825-835, 1991) is incorporated herein by reference. This article describes that pathologic analysis of the biologic effects and mechanisms of laser-tissue interactions requires correlation of the irradiation parameters with the biologic status and response of the target tissues over time. The photobiologic mechanisms of laser-induced tissue injury can be separated into three categories, photochemical, photothermal and photomechanical. Anatomic pathologic analysis of laser-induced lesions reveals alterations that represent either specific markers of the photobiologic mechanism or non-specific reactions to tissue injury. Repair, regeneration and wound healing of laser induced lesions appear to be non-specific responses to the type of tissue damage rather than the photobiologic mechanism producing the lesion.
An article authored by Jacques, Steven L. titled “Laser-Tissue Interactions: Photochemical, Photothermal, and Photomechanical” (Lasers in General Surgery, Vol. 72, No. 3, pages 531-558, 1992) is incorporated herein by reference. This article describes the variety of laser effects and how the characteristics of various lasers and various tissues allow different effects to occur. The authors approach the problem of laser-tissue interactions just like the novice, by turning up the laser power until something happens. However, in this article, they do not discuss thresholds but rather concentrate on what is going to happen.
An article authored by Manstein, Dieter et al. titled “Fractional Photothermolysis: A New Concept for Cutaneous Remodeling Using Microscopic Patterns of Thermal Injury” (Lasers in Surgery and Medicine, Volume 34, pages 426-438, 2004) is incorporated herein by reference. This article describes a new concept of skin treatment called fractional photothermolysis (FP), achieved by applying an array of microscopic treatment zones (MTZ) of thermal injury to the skin. Two prototype devices emitting at 1.5 μm wavelength provided a pattern of micro-exposures with variable MTZ density. Effects of different MTZ densities were tested on the forearms of 15 subjects. Clinical effects and histology were assessed up to 3 months after exposure. Treatment of photoaged skin on the periorbital area in an additional 30 subjects receiving four treatments over a period of 2-3 weeks was also tested. Tissue shrinkage and clinical effects were assessed up to 3 months after treatment. Pattern densities with spacing of 250 μm (microns) or more were well tolerated. Typical MTZ had a diameter of 100 μm and penetrated 300 μm into the skin. Reepithelialization was complete within one day. Clinical effects were assessed over a 3-month period. Histology at 3 months revealed enhanced undulating rete ridges and increased mucin deposition within the superficial dermis. Periorbital treatments were well tolerated with minimal erythema and edema. Linear shrinkage of 2.1% was measured 3 months after the last treatment. The wrinkle score improved 18% (P<0.001) three months after the last treatment. FP is a new concept for skin restoration treatment. Safety and efficacy were demonstrated with a prototype device. Further clinical studies are necessary to refine the optimum parameters and to explore further dermatological applications.
An article authored by Khan, Misbah Huzaira titled “Intradermally Focused Infrared Laser Pulses Thermal Effects at Defined Tissue Depths” (Lasers in Surgery and Medicine; Volume 36, pages 270-280, 2005) is incorporated herein by reference. This article describes a study to produce controlled, spatially confined thermal effects in dermis. A one-Watt, 1500-nm fiber-coupled diode laser was focused with a high numerical aperture (NA) objective to achieve a tight optical focus within the upper dermis of skin held in contact with a glass window. The delivery optics was moved using a computer-controlled translator to generate an array of individual exposure spots. Fresh human facial skin samples were exposed to a range of pulse energies at specific focal depths, and to a range of focal depths at constant pulse energy. Cellular damage was evaluated in frozen sections using nitro-blue tetrazolium chloride (NBTC), a lactate dehydrogenase (LDH) activity stain. Loss of birefringence due to thermal denaturation of collagen was evaluated using cross-polarized light microscopy. The extent of focal thermal injury was compared with a model for photon migration (Monte Carlo Simulation), heat diffusion, and protein denaturation (Arrhenius model). Arrays of confined, microscopic intradermal foci of thermal injury were created. At high NA, epidermal damage was avoided without active cooling. Foci of thermal injury were typically 50-150 μm (microns) in diameter, elliptical, and at controllable depths from 0 to 550 μm. Both LDH inactivation and extracellular matrix denaturation were achieved. Spatially confined foci of thermal effects can be achieved by focusing a low-power infrared laser into skin. Size, depth, and density of microscopic, thermal damage foci may be arbitrarily controlled while sparing surrounding tissue. This may offer a new approach for nonablative laser therapy of dermal disorders.
An article authored by Hedelund, L. et al. titled “Ablative Versus Non-Ablative Treatment of Perioral Rhytides. A Randomized Controlled Trial With Long Term Blinded Clinical Evaluations and Non-Invasive Measurements” (Lasers in Surgery and Medicine; Volume 38, pages 129-136, 2006) is incorporated herein by reference. This article describes a comparison of the efficacy and side effects of CO2 laser resurfacing and intense pulsed light (IPL) rejuvenation for treatment of perioral rhytides. Twenty-seven female subjects with perioral rhytides (class I-III) were randomly treated with either CO2 laser or IPL (three monthly treatments). Efficacy was evaluated by patient self-assessments and blinded photographs up to 12 months postoperatively. Side effects were assessed clinically. Non-invasive measurements included: trans-epidermal water loss (TEWL), skin reflectance, skin elasticity, and ultrasound. CO2 laser resurfacing resulted in higher degrees of patient satisfaction and clinical rhytide reduction compared to IPL rejuvenation up to 12 months postoperatively (patient evaluations, P<0.05) (observer evaluations, P<0.008). Laser-induced side effects included erythema, dyspigmentation, and milia whereas no side effects were observed after IPL rejuvenation. Non-invasive measurements showed a significant higher reduction of the sub-epidermal low-echogenic band in CO2 laser treated areas versus IPL treated areas (12 months postoperatively, P<0.001). Skin elasticity (expressed as Young's modulus) increased in both groups (P=ns). One month postoperatively a significant increase in TEWL values (P<0.009) and skin redness % (P<0.02) was found in CO2 laser treated patients versus IPL treated patients. No significant differences were seen in skin pigmentation % during the observation period. CO2 laser resurfacing induces a significantly higher degree of clinical rhytide reduction followed by considerably more side effects compared to IPL rejuvenation in a homogeneous group of patients.
An article authored by Laubach, Hans-Joachim et al. titled “Skin Response to Fractional Photothermolysis” (Lasers in Surgery and Medicine; Volume 38, pages 142-149, 2006) is incorporated herein by reference. This article describes Fractional photothermolysis (FP), a new concept using arrays of microscopic thermal damage patterns to stimulate a therapeutic response. They analyzed epidermal and dermal response to FP with the aim of correlating histological and clinical response. Twelve subjects received a single treatment with a prototype diode laser emitting at a wavelength of 1500 nm, delivering 5 mJ per microscopic treatment zone (MTZ), and a density of 1600 MTZs/cm2 on the forearm. Biopsies were procured over a period of 3 months. The biopsies were analyzed by two blinded dermatopathologists using hematoxylin and eosin (Hematoxylin and Eosin Stain), Elastica von Gieson, nitro-blue-tetrazolium-chloride (NBTC) viability, and immunohistochemistry stains. Furthermore, the treatment sites were evaluated in vivo by confocal microscopy. Twenty-four hours after fractional photothermolysis, the continuity of the epidermal basal cell layer is restored. Complete epidermal regeneration is obtained seven days after the treatment. Microscopic epidermal necrotic debris (MENDs) areas are seen as early as one day after fractional photothermolysis. MENDs contain melanin pigment, and are shed from the epidermis within seven days. Evidence of increased collagen III production is shown with immunohistochemistry (IHC) staining seven days after FP. IHC for heat shock protein 70 (HSP 70) shows the expression of HSP one day after fractional photothermolysis, and IHC for alpha smooth muscle actin shows the presence of myofibroblasts seven days after fractional photothermolysis. These findings are concordant with the induction of a wound healing response by fractional photothermolysis. There is no evidence of residual dermal fibrosis 3 months after treatment. A single treatment with fractional photothermolysis induces a wound healing response in the dermis. A mechanism for the precise removal of epidermal melanin is described, in which MENDs act as a melanin shuttle.
An article authored by Geronemus, Roy G. titled “Fractional Photothermolysis: Current and Future Applications” (Lasers in Surgery and Medicine; Volume 38, pages 169-176, 2006) is incorporated herein by reference. This article describes an alternative treatment for dermatologic conditions called fractional photothermolysis (FP). FP produces arrays of microscopic thermal wounds called microscopic treatment zones (MTZs) at specific depths in the skin without injuring surrounding tissue. Wounding is not apparent because the stratum corneum remains intact during treatment and acts as a natural bandage. Downtime is minimal and erythema is mild, permitting patients to apply cosmetics immediately after treatment. As with other nonablative laser modalities, multiple treatments are required. FP represents an alternative for treatment of dermatologic conditions without the adverse effects of ablative laser devices and can be used on all parts of the body. FP can be used for the treatment of facial rhytides, acne scars, surgical scars, melasma, and photodamaged skin.
Physician operators can achieve a favorable cosmetic outcome in patients by “painting” or moving the continuous-motion Fraxel Laser Treatment (FLT) tip, over the contours of the face and neck in multiple strokes. The result is a uniform glow on the face, neck, hands, or any body location with minimal risk of uneven pigmentation due to occasional under-treatment or over-treatment. Fraxel laser operators control dosage levels with the aid of a high-speed, beam-deflecting system and an intelligent optical tracking system (IOTS), which features compensation for the natural variation in hand motion. It monitors hand speed and tip direction by responding to the microscopic features on the skin (highlighted by a blue tint applied prior to treatment). Treatment density (micro treatment zones (MTZs)/cm2) level is maintained by the high-speed laser pattern generator built into the Fraxel handpiece. With the aid of patented beam-deflector technology, the Fraxel laser delivers up to 3000 precision pulses per second, more than 10 times the rate of conventional laser devices. The 15 mm treatment tip permits operators to cover up to 12 cm2 (˜2 in2) per second with a single pass. With this feature, FLT operators can treat the entire face and neck in 25 minutes and can treat larger off-face areas such as the chest, aims and legs. With traditional laser handpieces, treatment patterns are produced at target sites by stamping. When treatment is applied to adjacent sites, however, imperfect handpiece alignment results in the appearance of unwanted zones of demarcation. Furthermore, multiple stamping passes are necessary with traditional handpieces to attain the desired treatment density (MTZs/cm2) in a single treatment session. Multiple passes are excessively tedious and result in Moire artifacts. In addition, all treatment zones are laid down at the same time and bulk heating is avoided only by intense surface cooling at the expense of failure to coagulate the epidermis. Such treatment modalities, because they produce insufficient epidermal damage, cannot provide superficial resurfacing. In contrast, the Fraxel laser handpiece lays down individual MTZs sequentially in time, thus avoiding bulk heating and permitting more aggressive treatment of the epidermis and dermis. The randomized delivery also results in a macroscopically uniform treatment pattern. In addition, FLT's multi-pass technique allows the user to easily blend treatment zones and feather treatment edges.
U.S. patent application Ser. No. 11/747,711 titled “APPARATUS AND METHOD FOR A COMBINATION OF ABLATIVE AND NONABLATIVE DERMATOLOGICAL TREATMENT” by Leonard DeBenedictis et al. is incorporated herein by reference. This patent application describes a treatment for skin wherein a pattern of holes is ablated in a selected region of skin tissue using an optical source. Substantially nonablative energy is delivered to the selected region to at least two holes in the pattern to thermally heat a target in or just beneath the skin, such as hair follicles, sebaceous glands, or subcutaneous fat. The invention may further be improved by adding a feedback mechanism that adapts the nonablative energy in response to a measurement enabled by the ablation of holes. The apparatus may include a positional sensor to provide additional dosage control, particularly when the inventive method is used with a continuously movable handpiece.
U.S. patent application Ser. No. 11/749,066 titled “METHOD AND APPARATUS FOR FRACTIONAL LIGHT-BASED TREATMENT OF OBSTRUCTIVE SLEEP APNEA” by Leonard DeBenedictis et al. is incorporated herein by reference. This patent application describes an apparatus and method that uses fractional light based treatment to shrink soft tissue in the mouth or throat to reduce obstruction of the airways for patients suffering from obstructive sleep apnea. A light delivery probe with scanning optics can be used to deliver treatment. Cooling systems can be added to reduce damage to epithelial layers of tissue. Light based treatment can be nonablative or ablative and is preferably performed with a laser.
U.S. patent application Ser. No. 11/747,663 titled “APPARATUS AND METHOD FOR ABLATION-RELATED DERMATOLOGICAL TREATMENT OF SELECTED TARGETS” by Leonard DeBenedictis et al. is incorporated herein by reference. This patent application describes a treatment for skin containing selected targets that provides feedback in response to a measurement enabled by the ablation of holes. The inventive apparatus includes an electromagnetic source configured to emit ablative electromagnetic energy, a delivery system, a sensing element, and a controller. The delivery system can be configured to receive ablative energy from the electromagnetic source and deliver it to multiple discrete locations at the selected region to form a pattern of discrete holes in epidermal and dermal tissue of the skin. The lipid content a portion of the tissue can be evaluated using a sensing element. At least one pulse of electromagnetic energy is delivered to the skin under control of a controller in response to the result of a measurement by the sensing element. The apparatus may include a positional sensor to provide additional dosage control, particularly when the inventive method is used with a continuously movable handpiece.
U.S. Pat. No. 5,546,214 titled “METHOD AND APPARATUS FOR TREATING A SURFACE WITH A SCANNING LASER BEAM HAVING AN IMPROVED INTENSITY CROSS-SECTION” by Michael Black is incorporated herein by reference. This patent describes a method and apparatus for laser treatment of surfaces, such as tissue. In a preferred embodiment, the invention employs a unique reflective optical delivery system which produces an improved beam intensity cross-section which reduces thermal injury, increases the precision of the tissue interaction and allows the creation of craters with decreased sizes. Reflective optics provide precise, single-layer vaporization at low power levels without thermal injury to the underlying papillary dermis. Movable optical elements focus and direct the laser beam in a scanning pattern to treat a large area of the surface.
U.S. Pat. No. 5,151,098 titled “APPARATUS FOR CONTROLLED TISSUE ABLATION” by Hanspeter Loertscher; is incorporated herein by reference. This patent describes an apparatus for performing controlled tissue ablation in endolaser microsurgery, the apparatus including a laser delivery system coupled to a probe capable of transmitting the laser power through a suitable medium such as sapphire. The probe may include a central canal for aspiration and irrigation and delivers a cross-sectionally homogeneous power distribution. The apparatus is designed to control the ablation depth and to limit the zone of thermal damage in the remaining tissue.
U.S. Pat. No. 5,071,417 titled “LASER FUSION OF BIOLOGICAL MATERIALS” by Edward L. Sinofsky et al. is incorporated herein by reference. This patent describes an apparatus and methods for laser fusion of biological structures are disclosed employing a laser for delivery of a beam of laser radiation to an anastomotic site, together with a reflectance sensor for measuring light reflected from the site and a controller for monitoring changes in the reflectance of the light of the site and controlling the laser in response to the reflectance changes. In one embodiment, the laser radiation is delivered through a hand-held instrument via an optical fiber. The instrument can also include one or more additional fibers for the delivery of illumination light (which can be broadband or white light or radiation from a laser diode) which is reflected and monitored by the reflectance sensor. Reflectance changes during the course of the fusion operation at one or more wavelengths can be monitored (or compared) to provide an indication of the degree of tissue crosslinking and determine when an optimal state of fusion has occurred.
U.S. patent application Ser. No. 11/637,400 titled “SYSTEM AND METHOD FOR POINTING A LASER BEAM” by Steven Tidwell is incorporated herein by reference. This patent application describes an apparatus and method for directing a laser beam at an object. Some embodiments include generating direction-control information, based on the direction-control information, directing laser energy into a first fiber at a first end of a first fiber bundle during a first time period, forming an output beam of the laser energy from the second end of the first fiber bundle, and steering the output beam of the laser energy from the first fiber in a first selected direction of a plurality of directions during the first time period, and optionally modulating an intensity of the laser energy according to a predetermined pattern. The direction-control information is based on sensing electromagnetic radiation from a scene. Some embodiments use a remote camera wire-connected to the image processor to obtain scene information, while other embodiments use a second fiber bundle to convey image information from an external remote lens to a local camera.
U.S. Pat. No. 6,997,923 titled “METHOD AND APPARATUS FOR EMR TREATMENT”, U.S. patent application Ser. No. 11/235,697 titled “METHOD AND APPARATUS FOR EMR TREATMENT” and U.S. patent application Ser. No. 11/599,786 titled “METHOD AND APPARATUS FOR EMR TREATMENT” all by R. Rox Anderson et al., are incorporated herein by reference. This patent and these patent applications describe a method and apparatus for performing a therapeutic treatment on a patient's skin by concentrating applied radiation of at least one selected wavelength at a plurality of selected, three-dimensionally located, treatment portions, which treatment portions are within non-treatment portions. The ratio of treatment portions to the total volume may vary from 0.1% to 90%, but is preferably less than 50%. Various techniques, including wavelength, may be utilized to control the depth to which radiation is concentrated and suitable optical systems may be provided to concentrate applied radiation in parallel or in series for selected combinations of one or more treatment portions.
U.S. Pat. No. 7,292,232 titled “DATA INPUT DEVICES AND METHODS FOR DETECTING MOVEMENT OF A TRACKING SURFACE BY A LASER SPECKLE PATTERN” by Craig Ranta et al. is incorporated herein by reference. This patent describes a data input device for use with an optically rough tracking surface comprising a substantially coherent light source for projecting a substantially coherent light beam onto the tracking surface for scattering the substantially coherent light beam. An optic guides the projected substantially coherent light beam toward the tracking surface and comprises a first boundary facing the substantially coherent light source and a second boundary opposite the first boundary. A detector detects at least a portion of the scattered light beam comprising a speckle pattern. The optic is arranged such that the tracking surface is spaced from the second boundary by a distance sufficient to inhibit any substantial retro-reflection of the substantially coherent light beam striking the second boundary from striking the detector. A controller responsive to the detector operates the device in a tracking mode for utilizing the detected speckle pattern to track relative movement between the device and the tracking surface. The device is particularly useful in handheld and laptop devices, such as personal digital assistants, cellular phones, laptop computers, etc., where it is desirable to interact with a tracking surface comprising human skin, such as a fingertip.
In some embodiments, the Ranta patent provides an apparatus that includes a first fiber bundle having a plurality of light-transmitting fibers including a first fiber, a second fiber, and a third fiber, the first fiber bundle having a first end and a second end, a laser that emits laser energy, a processor that generates direction-control information, a fiber selector that is operatively coupled to the processor and based on the direction-control information, is configured to direct the laser energy into the first fiber at the first end of the first fiber bundle during a first time period, and transform optics located to receive the laser energy from the second end of the first fiber bundle and configured to form an output beam of the laser energy from the first fiber in a first selected direction of a plurality of directions during the first time period. Some embodiments further include a modulator that modulates an intensity of the laser energy according to a predetermined pattern. Some embodiments further include a sensor operatively coupled to receive electromagnetic radiation from a scene and to transmit sense information to the processor based on the received electromagnetic radiation, and wherein the processor is configured to generate the direction-control information based on the sense information. Some embodiments further include an ability to sense more than one object and simultaneously direct a plurality of laser beams in a plurality of different directions or sequentially direct a single laser beam in the plurality of different directions one at a time.
As used herein, a photothermolysis device is defined as any device that provides optical energy to cause dissociation, protein denaturation, or decomposition of animal tissue by heat. Conventional ablative laser technology causes heat damage to tissues surrounding the ablative site. There is a risk of infection and other side effects as a result. Conventional non-ablative-laser treatments provide less dramatic results. Fractional photothermolysis attempts to obtain the benefits of the two approaches described above.
There is a need for improved methods and apparatus for precision laser surgery. There is also a need for battery-powered, light-weight, portable laser surgery instruments. There is further a need for a plurality of modes of operation, including a cutting mode, a cauterizing mode, a fractional photolysis mode and/or the like.